This section provides background information to facilitate a better understanding of the various aspects of the invention. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
The invention relates to subsea well interventions, and more specifically to hydrocarbon evacuation of the production tubing to perform an environmentally safe well intervention.
Subsea wells are typically completed in generally the same manner as conventional land wells and are subject to similar service requirements as land wells. Further, as with land wells, services performed by intervention can often increase the production from the subsea well. However, intervention into a subsea well to perform the desired services is typically more difficult than for land wells. Conventionally, to perform subsea intervention, the operator must deploy a rig (such as a semi-submersible rig) or a vessel, as well as a marine riser, which is a large tubular that extends from the rig or vessel to the subsea wellhead equipment.
Interventions may be performed for various reasons. For example, an operator may observe a drop in production or some other problem in the well. In response, the operator performs an intervention operation, which may involve running a monitoring tool into the subsea well to identify the problem. Depending on the type of problem encountered, the intervention can further include shutting in one or more zones, pumping a well treatment into a well, lowering tools to actuate downhole devices (e.g., valves), placing the well on secondary recovery (e.g., installing an in-well pump), and so forth.
Performing intervention operations with large vessels and heavy equipment such as marine riser equipment, as conventionally done, is typically time consuming, labor intensive, and expensive. Therefore, a need continues to exist for less costly and more convenient intervention solutions for subsea wells.